Percutaneous transluminal angioplasty procedures have become commonly used in the treatment of various obstructive disorders of the human circulatory system. To date, angioplasty procedures have been utilized to treat stenotic lesions of the coronary arteries, iliac arterial obstructions, femoropopliteal arterial obstructions, renal arterial obstructions, cerebrovascular arterial obstructions, coarctations of the aorta, stenotic arteries in transplanted organs, stenotic saphenous vain bypass grafts, stenotic dialysis fistulas, stenotic portal systemic shunts and other obstructive vascular lesions.
In general, the usual technique for performing percutaneous transluminal angioplasty procedures requires the initial placement of an elongate flexible angiocatheter known as a "guide catheter". The guide catheter is initially inserted into an appropriate artery, such as the femoral artery or axillary artery, and subsequently advanced transluminally to a point where the distal tip of the guide catheter is positioned within a target blood vessel, near the obstructive lesion to be treated. A flexible guide wire is then inserted through the lumen of the guide catheter such that the distal end of the guide wire emerges out of and extends beyond the distal tip of the guide catheter. The guide wire is then advanced under fluoroscopic guidance, to a point whereat the distal end of the wire has advanced fully through the stenotic lesion or obstruction to be treated. After the distal end of the guide wire has been advanced through the stenotic lesion or obstruction, a small balloon catheter is then inserted and advanced over the guide wire, through the lumen of the guide catheter, to a point where the balloon of the balloon catheter lies adjacent the stenotic lesion or obstruction. Thereafter, the balloon is repeatedly inflated and deflated to bring about the desired dilation of the offending lesion and/or distention of the surrounding blood vessel wall. After such dilatory treatment is completed, the balloon catheter, guide wire and guide catheter are withdrawn and removed from the patient's body.
Various types and sizes of guide catheters are available. Care is generally taken, prior to the procedure, to pre-select a guide catheter of appropriate type and size for use in each particular patient. However, sometimes the pre-selected guide catheter proves to be inadequate and it becomes necessary or desirable to exchange one guide catheter for another during the course of the angioplasty procedure. If the decision to change a guide catheter is reached prior to insertion of the guide wire, the guide catheter may simply be extracted and replaced before the guide wire is inserted without any substantial risk of complication. However, if, as often occurs, the decision to replace the guide catheter is not reached until after the guide wire has already been fully inserted through the guide catheter and advanced through the stenotic lesion, any attempt to replace the guide catheter at that point is complicated by the need to maintain the previously inserted guide wire in its operative position, without accidentally pulling the guide wire back through the stenotic lesion.
In view of the foregoing problems in the prior art, there exists a need for a method and/or device to facilitate removal and replacement of a cardiovascular guide catheter while a flexible guide wire, which has been previously inserted through the lumen of the original guide catheter, remains in a substantially constant position without undue risk that the guide wire will be inadvertently pulled in a distal direction or otherwise pulled, retracted or jerked from its previously attained operative position.
The medical literature has previously reported two (2) techniques for removing an originally inserted guide catheter and replacing it with another guide catheter while maintaining the desired operative positioning of a previously inserted guide wire. One such technique is reported in: "Technique For Guiding Catheter Exchange During Coronary Angioplasty While Maintaining Guide Wire Access Across A Coronary Stenosis", by C. Mark Newton, M.D., Stephen A. Lewis, M.D., and George W. Vetrovec, M.D., Catheterization and Cardiovascular Diaonosis, 15:173-175 (1988). The first technique of Newton et al. requires the insertion of a relatively thick exchange wire be inserted and advanced through the lumen of the guiding catheter, beside the originally placed angioplasty guide wire. In particular, Newton et al. discloses the use of 0.35 inch diameter exchange wire which, when inserted through the lumen of the guiding catheter, lies adjacent to the existing angioplasty guide wire and provides necessary support during extraction and exchange of the guiding catheter. However, the passage of the exchange wire in immediate contact with the guide wire raises the possibility of inadvertent interference with and/or dislodgement of the guide wire. Moreover, the subsequent passage of the second guide catheter over the length of the existing guide wire and exchange wire may result in damage to or burring of the inner walls of the catheter.
The second technique for exchanging a guide catheter is described in "Guiding Catheter Exchanged During Coronary Angioplasty", by Stephen G. Warren, M.D., and J. Craig Barnett, M.D., Catheterization and Cardiovascular Diagnosis, 20:212-215 (1990). This second technique of Warren et al. is purely manipulative and relies solely upon the skill of the practitioner. The technique of Warren et al. requires placement of an extension wire on the proximal end of the original guide wire and, thereafter, the guiding catheter is slowly and carefully withdrawn while simultaneously forming a slackened area or "loop" in the guide wire within the ascending aorta. The slackened area or "loop" in the guide wire is formed to minimize the likelihood of inadvertent withdrawal of the distal end of the guide wire from its trans-stenotic position. After the first guide catheter has been withdrawn over the entire length of the extended guide wire, a second replacement guide catheter is then advanced over such extended guide wire and into a point where the distal end of the guide catheter is in the coronary ostium. Thereafter, the guide wire is gently retracted while the guide wire is simultaneously advanced through the ostium. By this procedure, the "loop" in the guide wire is eliminated and the new guide catheter takes its desired position within the coronary artery.
This second guide catheter replacement technique described by WARREN et al. is highly dependent upon the skill of the operator. Moreover, the technique described by WARREN et al. fails to provide any sort of enhanced support for the guide wire and, thus, allows the guide catheter to be moved over the thin guide wire without any protection or support for the guide wire.
One guide wire extension purported to facilitate exchange of a cardiovascular catheter with an existing guide wire in place is described in U.S. Pat. No. 4,917,103 (Gambale et al.). Another extendable guide wire for such procedures is described in U.S. Pat. No. 4,827,941 (Taylor et al.).
Other U.S. patents which purport to describe devices usable in exchanging cardiovascular catheters and/or guide wires are U.S. Pat. No. 4,927,413 (Hess) and U.S. Pat. No. 4,932,413 (Shockey et al.).
Because none of the prior art techniques or devices are truly optimal for effecting guide catheter exchange in all patients, there remains a need in the art for improved methods and/or devices for facilitating such guide catheter exchange without dislodging or disturbing the distal end positioning of a previously inserted guide wire.